Reproducibility of eucapnic voluntary hyperpnoea for exercise-induced bronchoconstriction diagnosis in asthmatic children and adolescents.

BACKGROUND: Respiratory symptoms after exercise are frequently reported by asthmatic patients, and exercise-induced bronchoconstriction (EIB) is a frequent cause, which requires objective testing for diagnosis. Eucapnic voluntary hyperpnea (EVH) is recommended as a surrogate stimulus for this purpose. Its short-term reproducibility is not yet established in children and young adolescents with asthma. OBJECTIVE: To evaluate the short-term test-retest agreement and reproducibility of FEV1 changes after EVH in this population. METHODS: Asthmatic patients aged between 10 and 20 years underwent EVH for EIB diagnosis on two occasions 2-4 days apart at a specialized university clinic. FEV1 was measured at 5, 15, and 30 min after EVH with a target ventilation rate 21 times the baseline FEV1 . EIB was diagnosed as a decrease ≥10% in FEV1 from baseline. RESULTS: A total of 26 of 62 recruited individuals tested positive for EIB on both visits (positive group) and 17 on one visit only (divergent group), while 19 tested negative on both visits (negative group). The overall agreement was 72.5% (95%CI 61.6%, 83.6%), and Cohen's kappa coefficient was 0.452. Low bias (0.87%) and high intra-class correlation coefficient (0.854, 95%CI 0.758,0.912; p < .001) for FEV1 response between test days were found, but with wide limits of agreement (±20.72%). There were no differences in pre-challenge FEV1 or achieved ventilation rate between visits either between groups (p = .097 and p = .461) or within groups (p = .828 and p = .780). There were no safety issues. CONCLUSIONS: More than one EVH test should be performed in children and young adolescents with asthma to exclude EIB and minimize misdiagnosis and mistreatment.

Exercise-induced bronchoconstriction diagnosis in asthmatic children: comparison of treadmill running and eucapnic voluntary hyperventilation challenges.

BACKGROUND: Exercise-induced bronchoconstriction (EIB) occurs in up to 90% of young people with asthma and can be diagnosed using serial measurements of forced expiratory volume in 1 second (FEV1) after standardized exercise, usually treadmill running (TR). Eucapnic voluntary hyperventilation (EVH) is a guideline-recommended alternative challenge for EIB diagnosis. The 2 methods have not been compared for EIB diagnosis in this population. OBJECTIVE: To compare 2 methods of EIB diagnosis in children and adolescents with asthma. METHODS: Thirty-four children 8 to 18 years of age attending the allergy clinic of the Hospital das Clínicas (Recife, Brazil) from September through December 2013 were examined. All underwent a basal FEV1 determination followed by TR for 8 minutes or EVH for 6 minutes on consecutive days. The first challenge was chosen at random. Serial FEV1 determinations were obtained at 3, 5, 7, 10, 15, and 30 minutes after the challenge and the test result was considered positive if at least 2 consecutive FEV1 measurements decreased at least 10% below the basal value. RESULTS: Thirteen patients responded to the 2 challenges, 6 only after TR and 4 exclusively after EVH (agreement 71%, κ = 0.41). The 95% limits of agreement of FEV1 decreasing after the challenges were widely spread (mean 0.1%, limits 19.8% to -19.6%). CONCLUSION: The 2 tests cannot be used interchangeably and the reproducibility of the FEV1 response to the EVH challenge has to be properly evaluated to better understand its role in EIB diagnosis.

Exercise-induced bronchospasm in children and adolescents with allergic rhinitis by treadmill and hyperventilation challenges.

BACKGROUND: Respiratory complaints after exercise are common in patients with rhinitis. Exercise-induced bronchospasm (EIB) may be one of the causes. OBJECTIVES: To evaluate EIB prevalence in a group of children and adolescents with allergic rhinitis, to compare the treadmill running (TR) and eucapnic voluntary hyperventilation (EVH) challenge methods as diagnostic tools and to assess the association between respiratory complaints on exercise and EIB. METHODS: Patients aged between 10 and 20 years were studied at the Pulmonology Department of the Hospital das Clínicas -UFPE- Recife, Brazil. The severity of symptoms of rhinitis and exercise-related respiratory complaints in the past year were evaluated. Challenges were performed in random sequence, no more than 72 h apart and followed international guidelines. Forced expiratory volume in the first second (FEV1) was determined before and 3, 5, 7, 10, 15 and 30 min after each challenge. A >10% reduction in FEV1 from baseline at two points after the challenge was considered sufficient to diagnose EIB. RESULTS: Of the thirty-five subjects evaluated, thirteen (37%) showed EIB, six by both methods, three only after TR and four only after EVH (Coens' Kappa = 0.489). There was no association between respiratory complaints after exercise and EIB (p = 0.74). CONCLUSION: A high prevalence of EIB was found in this population but only moderate agreement between the challenges used to diagnose EIB. Caution should be adopted when comparing these methods or interpreting their results interchangeably. There was no association between reported respiratory symptoms after exercise and EIB.